Love garlic too, but for me it's not enough to prevent the colds or flu.
Aside from washing my hands regularly and trying to not touch my face, I take Echinacea either when I start to feel a little anything slightly symptomatic and "pre-empt" by taking some before I go into public places where people sneeze and cough alot, which is most places.
If/When I do get symptoms, this recipe from an old woman at the Indian Grocery store, kept my young child and I out of the hospital when we were so congested the doctors wanted to admit us both. Take red lentils, wash repeatedly, then cook until they are tender, using only salt and black pepper. No spices, no onions, no garlic, veggies or anything else. Make a huge batch and drink the broth at least 4 big cups a day. The soup/lentils taste really nice too. Oh, yeah I do add American grown Saffron to keep the gassiness away.
It's amazing. We took that soup for 4 days, returned to the hospital for unrelated tests and the doctors thought I agreed to take the prescription they recommended for congestion. Ha-Ha! No need.
Keep well.
The other thing I noticed worked before, but I slacked off recently, was when I consistently exercised 1 1/2 hours day weekdays, including walking, a little aerobics, a little rowing. I was around obnoxious people who coughed and sneezed without covering up and did not catch anything.
Of course a vegan diet too.
Hoping we all avoid or minimize the flu and cold.
Cheers